This invention relates to the induction of blood vessel formation. More particularly, this invention relates to the induction of blood vessel formation in an animal by administering to the animal a sphingosine kinase, or an analogue, fragment, or derivative thereof. Preferably, the sphingosine kinase, or analogue, fragment, or derivative thereof is administered by administering to the animal a polynucleotide encoding a sphingosine kinase, or an analogue, fragment, or derivative thereof. The polynucleotide encoding the sphingosine kinase may be contained in an appropriate expression vehicle or expression vector, such as an adenoviral vector.
Vascular endothelial cells undergo morphogenesis into capillary networks in response to angiogenic factors. It was shown previously that sphingosine-1-phosphate, or SPP, a platelet-derived bioactive lipid, is an important sphingolipid-derived second messenger in mammalian cells that acts to promote proliferation and to inhibit apoptosis. (Olivera, et al., Nature, Vol. 365, pgs. 557-560 (Oct. 7, 1993); Spiegel, et al., J. Leukoc. Biol., Vol. 65, No. 3, pgs. 341-344 (March 1999).) Recently, SPP was defined as a novel regulator of angiogenesis. (Lee, et al., Cell, Vol. 99, No. 3, pgs. 301-312 (Oct. 29, 1999).) SPP activates the endothelial cell differentiation genes (EDG) EDG-1 and EDG-3 subtypes of G protein-coupled receptors on endothelial cells. Both EDG-1 and EDG-3 regulated signaling pathways are required for endothelial cell morphogenesis into capillary-like networks. SPP induces the Gi/mitogen-activated protein kinase cell survival pathway and enhances small GTPase Rho and Rac coupled adherens junction assembly. (Lee, 1999.) The level of SPP is regulated potentially by the enzyme that catalyzes the phosporylation of sphingosine to SPP. The cloning and characterization of the first mammalian sphingosine kinases (murine SPHK1xcex1 and SPHK1xcex2) has been reported. (Kohama, et al., J. Biol. Chem., Vol. 273, No. 37, pgs. 23722-23728 (Sep. 11, 1998)). Human sphingosine kinases (SPHK1 and SPHK2) have also been reported. (Nava, et al., FEBS, 473:81-84 (2000) and Liu, et al., J. Biol. Chem., 275:19513-19520 (2000).)
Applicants have discovered that the administration of sphingosine kinase, and in particular, that vector-mediated expression of sphingosine kinase enhances the formation of new blood vessels. Thus, the present invention is directed to inducing blood vessel formation in an animal by administering to the animal a sphingosine kinase, preferably by administering to the animal a polynucleotide encoding a sphingosine kinase or an analogue, fragment, or derivative thereof. The sphingosine kinase, or analogue, fragment, or derivative thereof, or polynucleotide encoding sphingosine kinase or an analogue, fragment, or derivative thereof, may be administered in combination with other angiogenic proteins or polynucleotides encoding other angiogenic proteins such as, but not limited to, VEGF, FGF, IGF, angiopoietins, PD-EGF, TGFxcex2, HIF1-xcex1, nitric oxide synthase, MCP-1, Interleukin-8, ephrins, NAP-2, ENA-78, GROW-2, and fragments of tyrosyl-tRNA synthetase that have angiogenic activity as disclosed in U.S. patent applications Ser. Nos. 60/193,471 filed Mar. 31, 2000, and 09/813,718, filed Mar. 21, 2001. The polynucleotide encoding the sphingosine kinase may be contained in an appropriate expression vehicle or expression vector, such as a viral vector. The administration of a polynucleotide encoding a sphingosine kinase to an animal is a method by which SPP can be delivered at elevated levels to a local site, and such method provides for the formation of larger vessels containing a well-defined structure that is supported by mural cells such as pericytes and smooth-muscle cells.